Hello all! New user looking for assistance troubleshooting a fet10e. Recently right channel began "making noise". Narrowed down with O-scope to sinusiodal inputs resulting in 1/2 wave rectified output. Further checking, it appears the output transistors Q8, Q9 are not biased on (comp1 voltage is ~0.4v, while on good channel it is around 0.88v). I suspect component hfe drift, possbily requiring adjustment of pot or component replacement.